Simplify the following expression: $z = \dfrac{10x}{7} + \dfrac{7x}{8}$
In order to add expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $7$ and $8$ $\lcm(7, 8) = 56$ $ z = \dfrac{8}{8} \cdot \dfrac{10x}{7} + \dfrac{7}{7} \cdot \dfrac{7x}{8} $ $z = \dfrac{80x}{56} + \dfrac{49x}{56}$ $z = \dfrac{80x +49x}{56}$ $z = \dfrac{129x}{56}$